This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Intramedullary nails are commonly used to provide fracture fixation. In the femur, antegrade intramedullary nails are inserted through a proximal entry hole. The location of the entry hole is typically either the piriformis fossa or the tip of the greater trochanter. Although the piriformis fossa is aligned more closely with the medullary canal, the greater trochanter is easier to locate intraoperatively. A known complication of this procedure is iatrogenic fracture of the femur, which some studies have shown depends on the entry hole location. It is the goal of this study to show how the stresses in the femur develop as the intramedullary nail is inserted, and how the stresses vary between entry hole locations. In our work to date (supported by Teragrid Grant Number MCB060034T), we have successfully compared the stresses between entry holes in a standardized solid model of the femur. To account for the considerable anatomic variation in human femurs, the next phase of this project will study the nail insertion in models of actual human femurs obtained from medical imaging data. CT scans of the lower extremity will be used to create finite element models from which intramedullary nails may be virtually inserted. The results of this study will show which, if any, morphological features of the femur impact the stress during insertion, and how these morphological features interact with a surgeon's choice of entry hole.